1. Field of the Invention
The present invention relates to an electronic doorbell circuit and more particularly to an electronic doorbell circuit that is adapted to be connected to one or more doorbell switches and a doorbell transformer that can detect when any one of the doorbell switches is depressed irrespective of the polarity of the diode, normally connected in parallel across one of the doorbell switches to provide electrical power from the doorbell transformer to the electronic doorbell circuit.
2. Description of the Prior Art
Electronic doorbell circuits are generally known in the art. Such doorbell circuits are normally coupled to a source of 120 volt AC electrical power and include a doorbell transformer for stepping down the 120 volt source voltage to a lower voltage, for example 16 volts AC or 24 volts AC. A secondary winding of the doorbell transformer is electrically connected to one or more doorbell switches and to a detector circuit for detecting when one of the doorbell switches is depressed to enable different tones or tone combinations to be generated to provide an audible indication of the particular switch depressed. In such known doorbell detector circuits, a diode is normally connected in parallel across one of the doorbell switches to develop a power supply for the detector circuit from the doorbell transformer. The polarity of the diode is determined by the detection circuitry. In known doorbell circuits, the detector circuitry is sensitive to the polarity of the diode, connected in parallel across one of the doorbell switches. With such circuitry, if the polarity of the diode is incorrect, the doorbell circuit will not operate.
Doorbell switches are normally located adjacent to doors and are thus remote from the balance of the doorbell circuitry. Although the diode across the doorbell switch can be preinstalled across the switch, the installer must correctly wire the switch with the proper polarity. As mentioned above, if the diode is installed with the improper polarity, the doorbell circuit will not work properly. As such, improper installation of the switch with the incorrect diode polarity can cause additional time and labor to reinstall the switch. In addition, when the doorbell switch is being replaced by a homeowner with little or no electrical experience, the potential for factory returns of the doorbell is increased, which, in turn, increases the cost of such doorbell circuits.